Which would be beeter of in place of my cast iron 6.0 heads? This will be on a cammed 6.0.

 

Why not go with 317s? Awesome heads, even in stock form.

 

A set of 5.3L heads (62cc chambers) are going to bump your compression ratio up by over a full point. This could cause problems if you plan on doing any towing. As mentioned, the 317 6.0L castings would be a good choice because you could keep your stock compression ratio (or raise it a little more by shaving the heads), have an aluminum casting, and have a set of heads that will move some air! The 317 castings flow some nice air just out of the box, but you could REALLY step it up with a ported set:

Trevor
Texas Speed & Performance

 

I don't have the aluminum version though I have the iron set. My motor is a 99-00. Would I be better off milling these down a little or going with the ls1?

 

You can pick up 317s for a couple hundred bucks, or can get a nice p&p set for $1200-2000.